Dissipative bracing system for post-tensioned timber framed buildings: Experimental testing of U-shape hysteretic dampers

This paper describes the experimental quasi-static tests performed at the structural laboratory of the University of Basilicata on hysteretic dissipative dampers consisting of Ushaped steel plates (U-shaped Flexural Plate) to be used for dissipative bracing systems. The cyclic tests, are preparatory for shaking table testing of a 3D, 2/3rd scaled, three-storey post-tensioned timber framed building equipped with dissipative bracing systems composed by V-inverted timber rods and two UFPs in series, designed for each storey to yield in a controlled manner. In order to optimize the design procedure of the UFP dampers, the analytical models available in the literature for the definition of the elastic stiffness and yield force of the devices are compared with the results of quasi-static experimental tests. Furthermore, in order to verify the robustness of the seismic protection technique, a parametric analysis is carried out considering non-linear numerical models, varying the characteristics of the dissipative bracing design parameters. Finally, the preliminary results of the shaking table tests on the braced structure are compared with those of the bare structure in order to validate the effectiveness of the dampers in the control of the seismic response.